litigious (adj.)

"fond of engaging in lawsuits," 1620s, from Middle French litigieux and directly from Latin litigiosus "contentious, quarrelsome," from litigium "dispute, strife," from litigare "to dispute, quarrel; sue, go to court" (see litigation). The word was in Middle English with a now-obsolete sense "fond of disputes" (late 14c.), making it senior in English to litigate or litigation. Related: Litigiousness; litigiosity.